feat: align LegacyHUB with TeamHUB platform contract (D2/D4, assets, security)

Close 12 audit-driven platform-compliance gaps on a single branch.

- D4 dispatch: app/integrations/dispatch_client.py participant `legacyhub`,
  emits LegacyhubDocumentIndexed + AssetDerivativeReady after the indexing
  commit (idempotent uuid5), http_inbox route (reindex/tombstone) with
  audit-based dedupe; docs/dispatch-contract.md. Celery+Redis stays intra-module.
- D2 SSO: app/integrations/identity.py validates X-TeamHub-* + role/scope
  mapper; security.py adds trusted-header enforcement (AUTH_REQUIRE_IDENTITY)
  and a scope check on /search; docker-compose.teamhub.yml (external teamhub_net
  + internal db net, api not host-published); RUNBOOK network/firewall section.
- Asset standard: SearchHit/Citation carry asset_id/owner_module; buckets
  renamed teamhub-legacyhub-* (+quarantine/tmp/exports); purge-by-asset_id with
  legal-hold guard (app/indexing/projection.py); OCR-markdown derivative event.
- audit_log model + Alembic 0003 + record_audit on writes (same transaction).
- Secret masking: app/common/json_logger.py recursive mask wired into structlog
  (+ensure_ascii=False); event payloads redacted before persistence.
- Service X-API-Key mandatory on ingest endpoints (defence-in-depth).
- Port: host API 8000->8050 (collision with SalesHUB/MailHUB resolved),
  container still listens on 8000.
- Config: no plaintext secret defaults; fail-loud in non-dev (no value leak).
- Docs drift: README PG 5440, layered-auth note, 5173 removed from CORS;
  ingest/folder gated by ENABLE_FOLDER_INGEST (410 by default).
- ADRs: layers mapping, shared-core extraction, UI locale (RU-first).

Tests: 78 passing (ruff, compileall, pytest, tsc, vite build, compose config).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/storage/minio_client.py

@@ -28,9 +28,18 @@ class MinioStorage:
         )
         self.originals_bucket = settings.minio_bucket_originals
         self.derived_bucket = settings.minio_bucket_derived
+        self.quarantine_bucket = settings.minio_bucket_quarantine
+        self.tmp_bucket = settings.minio_bucket_tmp
+        self.exports_bucket = settings.minio_bucket_exports
 
     def ensure_buckets(self) -> None:
-        for bucket in (self.originals_bucket, self.derived_bucket):
+        for bucket in (
+            self.originals_bucket,
+            self.derived_bucket,
+            self.quarantine_bucket,
+            self.tmp_bucket,
+            self.exports_bucket,
+        ):
             if not self.client.bucket_exists(bucket):
                 logger.info("minio.create_bucket", bucket=bucket)
                 self.client.make_bucket(bucket)